Boom-hoist safety means



June 4, 1 9- E. H. LICHTENBERG BOOM HOIST SAFETY MEANS Filed Feb. 1,1928 INVENTOR I Q E. H. Lichfenbe lq Patented June 4, 1929.

ERICH H. LICHTENBEBG, or MILWAUKEE,'WISCONSI1\T, ASSIGNOB T0 KoEI nINGcom PANY, or M LWAUKEE, wIseoNsIN, A CORPORATION.

BOOM-BOISE SAFETY MEANS.

Original application filed March 17, 1927, Serial No. 176,067. Dividedand this application filed February 1, 1928. Serial No. 251,108.

This application is a divisional case of my copending application,Serial No. 176,067, filed March 17, 1927 and relates to safety apparatusto be included in the structure of crane hoists. In the copendingapplication referred to, I have fully set out the means fordiscontinuing delivery of power upon the load on the boom exceeding acertain safe limit. This is carried out by short circuiting the powersource whether it comprises a gasoline plant or electrical motor, as theshort circuiting may take place in the ignition system of a gasolenepower plant.

This invention is directed more particularly to safety means that willfunction to discontinue delivery of power to the crane should the boomthereof be peaked past a certain predetermined safe angular position,-

and this means is incorporated with the overloading safety meansaforesaid and like the latter, functions by short circuiting the powerplant.

In attaining the end set forth, I avail of certain inherentcharacteristics of a crane construction to provide the. desired shortcircuiting of the electrical system included in the power plant. Thisfeature is the variation of the distance between the boom hoist cableand the boom. with variations in the angular position of the boom. Bypositioning a contact on the boom hoisting cable and including a secondcontact in the structure of the boom in spaced relation with the firstmentioned contact, these members will remain spaced apart so that theoperation of the machine is in no way interfered with so long as theboom stays within the limits of safety as regards its angular position,but should the boom become peaked too high. the con tacts aforesaid cometogether and thereby short circuit the electric circuit controlling thepower plant. a

Further and more detailed objects and advantages will in part becomeapparent and in part be hereinafter stated as the description of theinvention proceeds.

For a full and more complete understanding of my invention, referencemay be had to the following description and accompanying drawings, inwhich Figure 1 is a view in side elevation, somewhat diagrammatic of acrane'construction including the boom hoist safety means provided for bythis invention, the crane being shown in operating position.

Figure 2 is a view similar to Figure 1 showing the boom peaked past thesafety limit and the operation of the crane thereby discontinued. I

\"Vhile a preferred form of the invention is herein set forth, it is tobe understood that I am not to be limited to the exact constructionillustrated and described because various modifications of these detailsmay be provided in putting the invention into practise within thepurview of the appended claim.

A crane body is shown in the drawing somewhat diagrammatic anddesignated by the reference character A. This crane body is pivotallymounted in the conventional manner on a tractive support B. A boom C isoperated by a boom hoist cable D and may carry at its outer extremityany working tool such as a clam shell bucket E. The crane body A ismounted on its traction support so that it functions to counterbalancethe weight of the boom C, together with any load sustained thereby.Obviously, a highly unsatisfactory condition would result were the boompeaked past a certain safe limit as the weight of the crane body A wouldthen not be counterbalanced. To inhibit this condition I provide acontact 1 which is in appropriate connection with the electrical circuitincluded in the power plant of the crane body. If the power plantcomprises an integral combustion engine, the ignition system is usuallygrounded to the frame work of the machine. An engagement of the contact1 of the boom hoist will therefore discontinue op eration of the powerplant through the medium of short circuiting the electrical circuitthereof.

Should the power plant comprise an electric motor, a second contact maybe carried by the boom C and insulated therefrom that is adapted forcooperation with the contact 1 to short circuit the motor when thecondition arises for'such action.

The contact 1 may be carried in any suitable manner by the cable D suchas by the bail members 2 encircling the cable. Such a connection permitsof relative movement between the contact 1 and the cable D.

As set out in my copending application, the subject matter of thisapplication may be ed boom and a boom hoist cable, and means carried bythe boom hoist cable adapted for 10 contact -With the boom when the boomreaches its highest point of safe peaking, to discontinue operation ofthe boom from the source of power.

In testimony whereof I aflix my signature.

ERICH H. LICHTENBERG.

